The family of Charlie Dowd, 69, said Wednesday that Amtrak police told them that a passenger saw Dowd about 10 p.m. on Sept. 13 near a train door. Another passenger found an exterior train door ajar about 11 p.m. that night but didn’t report it to Amtrak officials until the next morning.

Yuma County, Colo., Sheriff Chad Day told NBC News that his agency on Tuesday finished searching by foot, ATV and even air the 40 miles of east-west track passing through his jurisdiction and had to tell the family and Amtrak police crews did not find Dowd.

“If I were in that position,” he said of Dowd’s family, “no one could do anything that would be enough. “Certainly from my perspective we did what we could do and that everything was searched that could be searched.”

Courtesy of the Dowd family

Charles Dowd, 69, a retired San Francisco firefighter and business owner en route to visit his son and family in Montreal, Quebec, Canada is missing.

Dowd boarded the California Zephyr on Sept. 12 in Emeryville, Calif., with plans to change trains in Chicago on Sept. 14 and continue to Montreal to visit his son. But when the train pulled into the Chicago station, Dowd was not aboard, yet his luggage, cell phone and medication were.

Amtrak on Wednesday told NBC News it was continuing to coordinate searches with local agencies as it has done since Dowd was reported missing.

Family members say they are concerned because Dowd, a diabetic, could potentially be disoriented and needing his medication.

“He’s a really independent spirit and was doing this trip for the adventure,” his daughter, Jennifer Dowd, told NBCBayArea.com. “This is a shocking turn of events.”

The train conductor said a person who fits Dowd's description appeared disoriented and confused about his whereabouts, thinking he was in an apartment rather than on a train and that he needed to find the front door. Police have yet to confirm the man the conductor saw was actually Dowd.